Humans use words like “always,” “never,” or “therefore” when we reason. Chimpanzees don’t have language like we do. But does that mean they can’t use logic? 

One experiment to test this is the classic three-cup task. On one side of the table, there is one cup and on the other side, there are two cups. We put a screen in front of one side at a time, blocking the chimps view- we show them a grape, and then hide it behind the screen under a cup, and then repeat for the other side. The chimp is then given a choice of which of three cups it wants. The single cup side is the best option, because there is only one place for the treat to be hidden- if they choose one of the cups from the pair, they only have a 50-50 chance of getting it right. However, chimpanzees don’t always pick the single cup! Why? Is this because they don’t understand the logic? Or could the task be too overwhelming to their brains?

My research explores this question by making the three-cup task less demanding. Instead of asking chimps to compare all three cups at once, we break the task into smaller steps. First, the chimp picks a cup from one side. Next, they pick a cup from the other side. Finally, they compare the two choices. 

By breaking the task into smaller steps, we can see whether chimps are able to reason logically when the task is less overwhelming. This helps us answer the question: are chimps really unable to use logic, or was the original task too tricky for them to show what they know? Which do you think?